


Genital Morphology and Copulatory Behavior of Galra

by Pi (Rhea)



Category: Voltron: Legendary Defender
Genre: Bonding, M/M, Mates, Mating Cycles/In Heat, Xenobiology, Xenophilia
Language: English
Status: Completed
Published: 2018-03-01
Updated: 2018-03-01
Packaged: 2019-03-25 11:46:50
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 8,642
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13833612
Author URL: https://archiveofourown.org/users/Rhea/pseuds/Pi
Summary: Keith learns some things about Galra biology and what that means for his relationship with Shiro.





	Genital Morphology and Copulatory Behavior of Galra

**Author's Note:**

> Or: xeno heat fic with a smidge of soulbonding, not ABO, does not contain mpreg (does contain mpreg potential), not canine-based.

The discomfort starts in the early afternoon. Keith doesn’t notice at first because he’s distracted helping Pidge. Apparently if he stands just so in the room it does something to the frequency array Pidge is working on, so of course Pidge has him wrapped in multicolored cables, holding three different tools, and feeling like he’s impersonating a Christmas tree. It isn’t bad. He’s feeling generally useful and Pidge is both entertaining and terrifying. Only, for some reason his body’s acting like he’s actually exerting himself. There’s sweat beading on the back of his neck and pooling under his armpits. When Keith shifts, the whiff of himself he catches is rank. He literally just showered this morning but he feels a sudden need to do so again, immediately. It doesn’t help that Pidge looks over and says,  
“No, wait, don’t move.” 

Keith freezes, both literally and metaphorically. The sweat cools clammy on his skin and where his shirt is sticking to him a little. 

“Is there a draft in here?” Keith asks, looking around with just his eyes so he doesn’t move. 

“Not that I’ve noticed,” Pidge shrugs. “Why?”

“It’s nothing, never mind.” 

Pidge raises an eyebrow at him but goes back to work. 

 

He feels somewhat better after taking another shower, the water hot and soothing on his skin. He’s still feeling colder than usual so he puts on an extra few layers before dinner. He starts with by layering his everyday clothes over his Blade uniform. When that’s not enough even with his jacket he wraps up in the blanket from his room. Maybe he’s coming down with something, but at least he’s feeling a bit warmer. He’s seen Lance wander around doing a burrito impersonation, there’s no reason Keith can’t do it too. Though his hair is still a little damp, he feels appropriately prepared to venture out. 

“Hey, cozy!” Hunk says when he sees Keith. Lance offers him a solidarity fist bump of blanket brotherhood. Keith returns it somewhat solemnly and feels generally good about his decisions, despite the way he’s faintly nauseous. 

“You’re a little flushed, are you feeling alright?” Allura asks worriedly over their meal. Keith tugs his blanket tighter around himself. He’s started sweating again, though it’s probably less noticeable when his hair is wet. Then Allura sniffs delicately in his general direction and Keith wants to melt through the floor in shame. Allura frowns, but she doesn’t say anything. Hunk is knocking Keith’s elbow on his other side and hasn’t reacted to it at all, but perhaps he’s too kind to say anything. Keith looks down at the food he’s failed to eat. 

“I think I’m going to go to bed, I’m not feeling great.” Keith pushes his plate toward Hunk.

“Aw, buddy, that sucks,” Hunk says and accepts the food. “Do you want me to try and make a soup type thing? We could probably manage a green goo soup, bring you some later, see how you’re feeling?”

“Yeah, thanks,” Keith mutters shuffling quickly for the door. He catches Shiro’s eye and Shiro shifts slightly as if to stand, but Keith shakes his head minutely. Both Shiro and Allura watch him go critically and Keith feels their stares long after he’s turned the corner and rustled off to his room. 

He’s not surprised then when there’s a light knock at his door. It’s too hesitant for Shiro whose knock is more of a “hi I’m coming in” than a “are you going to answer the door?” Keith stares at the door willing it to open with his mind. Getting up seems like it’d be a lot of work and his insides are cramping uncomfortably. If he’d eaten much of anything Keith would suspect food poisoning. He hobbles to the door.

“Oh dear, you don’t look good,” Allura says, taking his shoulder and steering him back to the bed. She helps him lay back, then leans forward and inhales. Keith sputters but she only nods thoughtfully as she pulls away. “Well, this is a bit unexpected but I’ll contact the Blade of Mamorra right away, I’m sure they’ll be able to advise us.”

“What?” Keith glares, “What do you mean?”

“Well, I’m certainly not an expert in Galra biology, I can make a few informed inferences but I’d rather someone who knows a bit more about their species weigh in. How are you feeling?” 

“Lousy,” Keith admits. 

“Yes, you well might. I’ll ask Coran and see what we might have for you in the meantime.” Allura looks around his room, “Are you most comfortable here? Is there somewhere else in the Castle you’d like to be?” 

Keith shrugs, it’d be too much work to go anywhere else, really. 

“Right of course, you’ll have more energy later I’m sure.” She pats his shoulder fondly. There’s something calming about the pressure of her touch even through all the layers. Keith draws in a steadying breath. Allura smells so clean, a distinct authoritative scent that’s almost pretty. It’s something to focus on in the muddied assault of all the other smells around him: metal, and fabric, something chemical: both astringent cleaning chemicals and a burning electrical smell. 

“What’s happening?” Keith asks, turning his head slightly to follow her withdrawing hand. 

“Well, I assume humans have some sort of fertility cycle?” Allura asks. Keith blinks at her. “The Galra will know.” She smiles, leans back in to squeeze his arm slightly, and leaves him tired and deeply concerned in his room. 

 

Keith does not feel better in the morning, at least not the early morning. He’s woken up out of a fitful sleep by his muscles shrieking like he’s been stabbed. Sharp throbbing pain roles through him but doesn’t seem to be located anywhere more particular than below his neck and probably above his knees. Keith tries laying flat and still but it doesn’t help, so he curls up into a ball still wearing almost all the clothes he owns and wrapped in his blanket. It takes him a long time before he falls back asleep. 

When he wakes around what’s probably mid-morning he’s physically exhausted, but he feels much better. Clearly he’d been functioning on a slower speed yesterday because only now do Allura’s words click into place in his head. Keith has had human biology courses. The Garrison had covered sex ed with the same efficiency and practicality that they approached all classes. Keith is certainly aware of the important information: primarily that this isn’t typical of human male behavior. On the other hand, Keith is feeling much better. Now that he’s sitting up, his energy seems to be flowing back into him. Maybe Allura was wrong. Keith knows there’s potential for serious weirdness, being part Galra, but he would have noticed before this right? Keith takes a quick, hot shower, mostly just scrubbing at his armpits and relishing in the blissful warmth of the water. He puts on his other Blade uniform because everything else is now dirty and follows his stomach to get some food. Hopefully he can correct Allura before she goes too much further into her theories. 

Allura has taken her theories and run with them. Keith gets partway through a bowl of green food goo before Kolivan enters. It’s still surreal to see a Galra in the Castle of Lions, even if Keith doesn’t have the same prejudices that Allura carried. The fact that Allura is standing nervously behind Kolivan as she ushers him in is even more disconcerting. 

“I believe it started yesterday, he was quite flushed at dinner and drained of energy when I checked on him later.” 

“Keith,” Kolivan says, coming to stand next to him. 

Keith puts down his spoon. He swallows his bite of food goo, jerking to a stand. 

“Have a seat,” Kolivan directs, sitting himself. He looks at Allura, his eyes sharp, “These are not secrets, you may stay if you wish.”

“I find it quite fascinating actually,” Allura says and pulls out her own chair. 

Kolivan turns to Keith, “When our young mature to a certain age, they may become fertile. This fertility has cycles once it is triggered. If the impetus for the fertility is removed an individual’s fertility may become dormant again. I am not certain how this would be impacted by your human physiology. If you are willing, we would like to take you to our medical staff.”

Keith looks to Allura who shrugs, “I feel much better…” Keith hedges, “would it be alright if I don’t?”

“I would hope so.” The doubtful tone of Kolivan’s voice makes Keith’s shoulders slump.

“I’ll go with you,” Keith acquiesces.

Allura frowns, “You should take someone with you. We’ll bring the castle nearby, but someone should still go with you.” Allura glances at Kolivan, “We trust you of course, but another paladin may provide moral support, as well as be able to relay any important information to the rest of Voltron.” 

Keith bites back a grumble about his ability to represent himself thank you. Allura is polite enough, savvy enough to work graciously with the Blade, but that doesn’t mean she won’t hedge her bets and Keith appreciates both the implied inclusion of him as one of Allura’s own, and the subtle support she’s offering him.

“Oh, Keith, you’re up,” Shiro says from the doorway in truly spectacular timing. “Kolivan. Allura.” Shiro nods to the room’s other occupants, concern growing on his face. “Allura said you still weren’t feeling well last night.” Shiro looks between them all, “What’s going on?” 

Kolivan’s piercing gaze narrows on Shiro. Shiro squares his shoulders against it, jaw setting.

“I see, you’ll be Keith’s companion then?” 

Shiro flicks his gaze from Kolivan to Keith for a fraction of a second, “Of course.” 

Allura rises. “I’ll go see to the Castle. We’ll be there shortly. You two should prepare for your trip. Will it be very long, Kolivan?”

“A day or two at most.” Kolivan inclines his head slightly to Allura and she returns the gesture almost formally before she leaves. 

 

“What’s going on Keith?” Shiro asks when Keith climbs into the black lion behind him. “Are you alright?” 

Keith sags back against one of the consoles, he’s starting to feel a little shaky. There’s none of the nausea from before, though he still isn’t hungry and hasn’t eaten more than a single bowl of green goo food in total since lunch yesterday. The tremors are almost as if he has too much energy. Keith jogs his foot slightly, shaking out tension. He’s sweating again. At least the black lion smells good, much better than the castle.

“I don’t exactly know yet.”

Shiro frowns, “Is it serious?”

“How can I know if it’s serious if I’m not sure what’s happening,” Keith snaps. He blows out a frustrated breath, “Sorry, it’s just stressful.” 

Shiro is still frowning, but he reaches out a reassuring hand to cup Keith’s neck. Keith melts against it, dropping forward so his head can rest against Shiro’s shoulder. Shiro strokes over Keith’s hair and Keith breathes deeply, trying to calm his racing heart. 

“Is there anything I can do to help?” Shiro asks. Keith shake his head. His forehead rubs against the fabric of Shiro’s shirt. At least Shiro still smells amazing. Keith breathes in, grounding himself against Shiro’s familiarity. In this, as in all things, Shiro can be his rock.

“No. This is good. You are helping.” It’s true. Keith is starting to feel better, and also like he wants to curl up in Shiro’s lap and never ever leave, but that isn’t new. If Keith wasn’t so gross he probably would do it too. “Sorry I stink, apparently that’s a side effect,” Keith mutters instead.

Shiro takes an obvious breath, “Mm, nope. You smell great to me.” Keith shifts back to look at him. Shiro grins. He leans forward briefly to drop a quick kiss on Keith’s cheek. “Come on, let’s get you to the doctor and we’ll figure out what’s going on.” He gives one hand to Keith to hold, guiding Black one-handed out into the star field. Keith slides down to the floor, until he can curl up against the side of the pilot seat and rest his head on Shiro’s knee, keeping his fingers tangled with Shiro’s. He falls asleep sometime before Shiro’s hand leaves his.

 

Keith wakes up when the Galra medical bot starts poking him. He flails awake half coherent and coursing with fury and terror.

“Keith!” Shiro’s voice cuts through. A familiar hand grips his forearm and Keith stops lashing out. The medical bot has managed to duck him and is floating a safe distance away near two members of the Blade Keith doesn’t know well. Shiro’s hand slips away and Keith collapses back against the bed, the world shifting back out of focus slightly. He doesn’t attack the medical bot again. Instead he lays still and inwardly curses his Galra biology. Keith ignores the poking of the medical bot until Shiro tells him to stand up so the medical bot can do a second set of tests. Keith sighs but follows the instructions. A few minutes later Shiro sits him back down and picks up his hand.

“Are you ready to hear what the doctor has to say?” 

Keith suspects Shiro doesn’t feel ready, if his grip on Keith’s hand is any indicator. Of course, Shiro doesn’t have the benefit of an inkling of what this all might be about. Keith feels vaguely bad about that. 

“So,” the doctor begins, “it is clear that a certain part of your Galra heritage is making itself known. Once we reach an age of maturity, all Galra enter a breeding phase of life, which means they have the potential to be fertile. Is that similar to the experience of humans?”

Shiro shakes his head. “For some humans, yes, but Keith wouldn’t. Keith isn’t the kind of human that could carry children.”

“Oh, of course carrying a child isn’t necessary for Galra either. It just means an individual is viable for either giving genetic material for a child, or gestating one themselves,” the doctor hurries to explain. “For humans is there a specific trigger for their fertile times?”

“For humans that carry children It’s, ah, cyclical I believe, after a certain age. Monthly? Every pheob?” Shiro says. 

“Well, that is certainly uncomfortable!” the doctor declares, making a disapproving clicking sound in his throat. “For Galra, fertility is only triggered in the presence of a potential mate. The process is too costly to our energy otherwise. Once a mate is found as long as the pair couples routinely their fertility will remain dormant, but should mates, or potential mates experience prolonged exposure to one another without copulation that will induce fertility and they may then choose to breed and form a mating bond.” 

Keith glares at the doctor because the only people he’s been around since he returned to the Castle are there rest of Voltron. He and Shiro have had sex, maybe not really recently since things have been hectic for a while, but somewhere in the last few weeks. Keith really doesn’t want to find out there’s someone else on the team some bizarre facet of his Galra biology has chosen to react to. He’s not in a relationship with anyone else, he doesn’t want anyone else. Keith looks at Shiro, his face feels like it’s crumpling. Shiro isn’t looking back at him, his eyes are trained on the doctor. 

“What do we need to do?” 

“It would be good to identify the inducer. If the match is acceptable we have a serum that can be used to prevent conception. An exchange of genetic material would be best, and the most efficient way if there is a match that would abate your present fertility. If the match is unacceptable we do have treatments which will lead to dormancy of your fertility but it would not solve the potential longterm problem and the two individuals would likely need to be separated. You could of course choose to live in a fertile state, but as you can see it isn’t the most comfortable.”

“How do Galra handle this?” Keith demands. 

“We bond rarely. Our lives are long enough there is no immediate drive to find a mate. If the time is inopportune, Galra simply avoid that potential match. Most Galra recognize that it happens infrequently, so we change our lives accordingly, whether to accommodate a bondmate or to permanently separate from that person.”

“But I don’t want to leave,” Keith says, gaze dropping down to where his fingers are tangled together around Shiro’s.

“Let’s find out who it is first, alright,” Shiro says and squeezes Keith’s hand. Keith nods miserably while Shiro goes with the doctor to relay how to best collect genetic samples from the rest of Voltron. 

Keith curls into a ball on slab-like hospital bed. He feels at once muzzy and tired but also like, if given the right prompt, he could run a marathon. Unspent energy sits in his muscles twitching, but his bones are like lead and his head is swimming. He can’t seem to get comfortable and Shiro and the doctor are taking forever to come back. Keith scoots down from the bed-table and tucks himself up on the chair Shiro had been sitting on earlier, which is slightly better. He breathes deeply and rests his head on his knees to wait. 

 

Shiro’s hand on his shoulder arcs him back to the present like a live wire. Keith stumbles out of the chair and shakes what might be pins and needles from his arms and legs. 

“What’d you learn?” he asks, though part of him doesn’t want to know. Shiro’s expression is carefully neutral. 

“The tests can only serve as an indicator,” the doctor cautions, “and we can’t be sure how accurate they are given how different the biology of you humans is.” The doctor frowns as if human genetic make up personally offends him. “There are a few other indicators you can use to corroborate our results.” The doctor looks to Shiro who nods for him to continue, eyes still locked on Keith’s reactions. “A compatible mate will likely be someone you’ve been in close contact with. As your symptoms progress, their presence will provide some stability and clarity.” Keith thinks of Allura the night before and his heart sinks. “This may be a literal clarity, by dominating and obstructing your senses with their presence they bring a level of focus that can assist with vision or smell. Their personal scent will likely become appealing, more prominent to you. Does any of this fit with your experiences?” 

Slowly, Keith nods yes. He turns to Shiro with hope bubbling up, waiting to flow over into relief. “It’s your sample that’s the match, isn’t it?” 

Shiro nods carefully. Keith doesn’t understand why Shiro isn’t touching him. If Shiro’s the match that’s great, that's amazing. It means Keith doesn’t have to leave Voltron again. Why isn’t Shiro doing anything?

“Keith,” Shiro says slowly, “the doctor explained how the changes your body is going through can be mind altering. There’s a biological imperative…” 

“What is the problem?!” Keith demands, “I get we’ve been really busy late and maybe sex hasn’t been _your_ priority recently. Which!” Keith holds up a hand to forestall Shiro’s protest, “I completely understand. Our work as Voltron comes first. But what I’m saying is this wouldn’t be that different.” 

Shiro clears his throat and looks back to the doctor. Keith turns to glare at the doctor as well.

“A proper matched mating has consequences.”

“I thought you said I wouldn’t get pregnant.” Keith crosses his arms over his chest and keeps glaring.

“We can help you prevent conception, however, a mating bond has just as long term an impact as conceiving a child.”

“Mating bond?” Keith repeats. 

“Do humans mate for life?”

“Not exactly? Some couples do stay together for the length of their lives,” Shiro explains.

“Galra may choose not to spend their life with a bondmate, but that bond will last until the death of a partner,” the doctor nods to himself.

“But what does that mean, what does it do?” 

“It connects the two people through their quintessence. I have heard,” and here the doctor drops his voice low, “that the druids have discovered how to break the bond.” He shudders in horror, “That they use the energy released to power some of their spells. For most of us though it means we are aware of our bondmate. We know their distance from us, we know their needs, though that knowledge is not overpowering and is easy enough to ignore, much like one’s own mild hunger or thirst. Those with particularly strong bonds will have a general sense of feeling, joy or sorrow. Some bonded pairs are able to control how they share quintessence. There are old stories of strong fighters made exponentially more powerful through receiving their bondmate’s strength, though of course there is no credible evidence to these stories.” The doctor shrugs. 

“Keith, I want you to know you have a choice,” Shiro says. “You can stay with the Blade for a while, it’d only be a few weeks if you go through their treatment. We could work out something so we trade off time with Voltron, and we could still be around each other for short periods of time. It’s prolonged exposure that’s the issue. Or even once you go through the treatment and all this is past, if we start having regular sex, it won’t become an issue again because your Galra fertility will still be dormant. You don’t have to do this now.”

“What if I want to?” Keith asks. 

“But you don’t know that, Keith. This is like being in heat right?” Shiro looks at the doctor, “You said it would influence him.”

The doctor shakes his head. “Fertile Galra are fully competent.” The doctor smiles, “There is a famous story of star-crossed lovers: she lead a revolution even though her potential mate was of the ruling guard she rose against. Their love was strong so they could not help but met routinely but they were both warriors for their ideals and kept chaste for their causes: separated by ideology but bound by their emotions.” The doctor seems to realize he’s waxing off topic and quickly concludes. “She strategized her way to victory, but her mate was executed before they could be reunited as lovers.” 

“See, totally competent,” Keith points. “The question is do you want to?” Keith can’t stop his voice from going hesitant at that. What if Shiro doesn’t want to. 

“I do.” Shiro cuts across Keith’s thoughts before he can worry further. “This isn’t how I imagined saying it, but I love you Keith.” 

Keith draws in a sharp breath before stepping forward and pulling Shiro into a hug. And, fuck, of course it’s Shiro. Shiro smells amazing, his hand is hot and perfect against the back of Keith’s shoulder. A bolt of lust shoots through Keith leaving fire in his core. He leans up for a quick, impulsive kiss but Shiro pushes him gently away. 

“I think there’s something else we need to do first.”

“I’m not going to get pregnant from kissing you,” Keith grouses but lets Shiro redirect him back towards the doctor. “Alright, how do we do this?”

“We’ll administer the serum into your abdomen.” The doctor waves over the medical bot and gestures for Keith to open his Blade uniform. “Then it would be wise to give you both hydration boosters. You’re likely haven’t been feeling hungry?” the doctor asks and Keith nods.”It is a side effect. Since you will not be intending to conceive, we should add nutrient boosters in with that.” 

Keith shrugs, “Fine.” The medical bot approaches him with a star shaped cluster of prongs. Keith jerks back. 

“It’s only temporarily numbing the area,” the doctor soothes, which isn’t actually very reassuring. The bot’s prodding tickles a little and then it switches appendages and jabs him with something long and thin. Keith can’t feel anything, which he supposes is good because that is an awful lot of long hair-thin thing going inside him. When it retracts it’s almost like watching a measuring tape slide back home. The bot runs a little flash of purple light over the spot and then retreats, hovering up back into its standby mode. Keith pokes the area gingerly but he can’t feel any hole and the area is no longer numb. 

“Okay.” Keith looks back at the doctor, “is that it? Is there anything else?”

“We will lead you to an appropriate accommodation.” 

 

An appropriate accommodation turns out to basically be a room with a collection of gray squishy vaguely flat hexagons which are piled together into a sort of nest or reclining area. It is both comfortable and a place a person could lay down. 

“What should I expect?” Shiro asks completely seriously while Keith shifts awkwardly behind him. 

“Contact without obstructing clothing will help initiate the bonding. It will require an exchange of genetic material between you, from each to each.” The doctor makes a thoughtful noise, “Beyond that I imagine it is similar mechanics. You said humans don’t bind their quintessence? A mating bite is traditional for Galra bonding.” The doctor shows his teeth in what might have been a smile on a human but when filled with sharp Galra points leaves a rather different impression. 

“Okay,” Shiro nods slowly. “Thank you. Now if you’d…?” Shiro looks from the doctor to the door.

“Of course.” 

Keith stares at Shiro, Shiro stares back. Keith hasn’t felt awkward like this around Shiro in years, since well before they’d started their relationship. It’s strange that this should feel so much more fraught than the actual first time they had sex. Of course, the words "mating bond" are rattling around in Keith’s brain this time.

“I want this,” Keith says just to be clear. “I want you. Do you-?”

“Of course.” Shiro closes the distance between them and this time he kisses Keith. The arousal from before comes roaring back to the surface. Keith’s fingers dig into Shiro’s hair and his whole body thrums in approval. 

“Naked, I want you naked.” Keith wrenches himself away, tearing at his own clothes while he flaps a hand for Shiro to do the same. Shiro isn’t nearly so frantic in his haste to get undressed, but then again Keith is naked and running his hands over every inch of skin Shiro exposes, so that might be somewhat distracting. Shiro is gorgeous, always had been. He’s a miracle of muscle and scar tissue, dips and planes Keith’s fingers already know but thrill to discover again. It is as if everywhere they touch energy arcs between them, little shocks raising pleasure across Keith’s skin. 

“He said we have to both exchange genetic material. But we didn’t confirm how…” Shiro frowns. Keith pinches one of his nipples.

“Shiro, fuck me.” 

Shiro’s eyes go hot on him and he pulls Keith into another kiss. The both of them trip backwards down into the pile of cushiony hexagons. There’s a bit of a holdup when they identify the lack of lube. 

“I’ll ask.” Shiro sighs, making to stand up. 

“Maybe Galra don’t-“

“You’re human too. And we obviously still need it.” Keith squirms a little at the spit slicked press of Shiro’s finger inside him but Shiro’s right. 

“I’ll be right back,” Shiro presses a quickly kiss to Keith’s lips in apology.

 

When Shiro comes back, bare chested and with barely buttoned pants, Keith unburies himself from where he’d been using the cushions to feel a little less exposed.

“How’d it go?”

“Apparently Galra have more natural fluid secretion than we do. But they did have a medical ‘sliding gel’ which seems about right.” Shiro looks down at a shiny smear on the back of his hand. “We’ll check if you’re reactive.” 

Keith holds out his hand and sighs. He gets distracted making out with Shiro and letting his hands wander where they please, while they wait. The gloriously heightened sensation of Shiro’s skin along his body is thoroughly engrossing and Keith breathes in the hot heady taste of Shiro from the close air. He almost forgets what they’re waiting for, that there could be more than Shiro’s scent wrapping around him completely and Shiro’s arms holding him tight. 

“Looks good,” Shiro says when he shifts back. “Are you ready?” 

Keith let’s his legs fall open in answer, lifting his hips up a bit so Shiro can position him for better access. Shiro leans down to kiss him again, this time with slick fingers circling their way home and pressing up into Keith. Shiro gets two fingers in and it’s like a switch flips somewhere in Keith. He goes from panting and pleasure soaked to desperately hard and completely sure if he does not get Shiro into him right now he is going to die. 

“Now, Shiro.” Keith growls. His nails dig into Shiro’s hips as he hauls him closer squirming forward like he could wriggle himself right onto Shiro’s dick. 

“Fuck, Keith,” Shiro gasps. The drag of his fingers leaving Keith’s body is excruciating but then there’s blunt pressure and Shiro is easing inside him. Keith tries to slam his hips flush against Shiro, but Shiro’s strong grip keeps him pinned in place as Shiro works further inside him so painfully slowly. Keith cries in frustration, head tossing and body shaking because it’s not enough, not yet. Shiro leans down to dust kisses over Keith’s chin and cheek. 

“Please,” Keith begs and Shiro starts to slide out of him. Keith jolts clawing frantically as he tries to keep Shiro in place. Shiro snaps his hips forwards and that’s much better. Keith’s body bows and he cries out. Shiro does it again. His thrusts are small and sharp as he sets up a rhythm. It sparks through Keith’s body, lighting him up from within even though Keith is fairly certain Shiro hasn’t hit his prostate yet. Once Shiro’s found their rhythm it’s easier to move with it. Some part of Keith is lulled that Shiro isn’t going anywhere. Shiro leans over him and Keith raises up, wrapping his arm around Shiro’s shoulder and gasping into his neck while Shiro murmurs _I love you_ ’s into his ear. Keith can’t help clenching down around Shiro. It’s overwhelming, the feeling of so much of Shiro’s skin against him, the way his scent is everywhere soaking into Keith’s skin like he’ll be able to wear it. 

“Please,” Keith pleads again, voice going wet and soft. Shiro grunts and swears and his hips slam forward. With Keith clinging to him, the angle has changed so Shiro’s dick presses against Keith’s prostate. Keith keens. He’s tilting dangerously on the edge of orgasm. 

“Keith,” Shiro moans and Keith is so hypersensitive he feels the minute twitch of Shiro’s dick inside him, another brush against his prostate, and the first pulse of Shiro’s come. Keith’s orgasm rips through him and he involuntarily bites down hard at the join of Shiro’s neck and shoulder. It wrings through him, shaking and shaking until Keith collapses back, Shiro coming with him. Keith slowly loosens his jaw and draws back. His teeth leave behind a blood red mark. 

“They did say mating bite.” Shiro lifts a tentative hand to the wound. “How does it look? I…can’t actually feel it.”

“What?!” Keith demands.

“It hurt only for a second, but then I couldn’t feel it anymore. The whole area is sort of warm, throbbing? It’s not painful though.” 

“You’re bleeding. I bit you and you’re bleeding.”

“Your teeth are fairly sharp, for a human. It’s fine Keith. We’ll have the doctor look it when we’re done.”

“…when we’re done?” 

“You haven’t come yet, and…” which was the point Keith looks down at his lap incredulously, because he could have sworn...and then he proceeds to freak the fuck out. 

 

“Yes, that is common Galra physiology. They stimulate ovulation in a fertile mate.” 

Keith no longer cares that he's standing stark naked in front of a strange Galra. They're all getting an extreme overview of the mismatches between human and Galra breeding practices might as well have it all on display. 

“What the fuck.” Keith asks, or says, it’s all fairly the same at this point. 

“Keratinized penile spines. Your body has reacted to your beginning consummation of the mating bond. I assume this is unusual for humans? They should do your partner no harm, they simply stimulate the-“

“How do I make them go away?” 

“I’m sorry?” the doctor looks from Keith to Shiro.

“You’re correct that humans don’t typically have.” Shiro gestures. The doctor keenly observes Shiro’s very human dick leaning forward slightly. 

“Will it prevent your copulation?” They all look at Keith’s genitals which are still in a full state of arousal despite everything. Keith groans into his hands and turns into Shiro’s side. The doctor offers, “When in dormant fertility there are cremes which will help resoften the skin to it’s original state.” Keith beats his head softly against Shiro’s shoulder. His crotch brushes slightly against Shiro’s leg. Fuck. 

“They’re not sharp.” Shiro observes.

The doctor nods, “The roughness adds a texture necessary to stimulate ovulation, and of course they help with the genital lock.” 

Keith and Shiro share a look.

“Maybe I’ll just blow you,” Shiro offers. “Would that qualify for an exchange of genetic material? Galra and humans obviously don’t have precisely the same parts, would it make a difference how genetic material was exchanged?”

“I don’t understand?” The doctor frowns at Shiro.

“Oral.” At the continued lack of comprehension on the doctor’s face Shiro sighs. “If I were to stimulate his genitals with my mouth to the point of excreting genetic material would that be an acceptable way for me to receive that genetic material. They’re both digestive tract but I have no idea what makes a difference in this case.” 

The doctor is staring at the wide-eyed, “Humans do that?” Keith considers what he has seen of Galra teeth and figures the doctor has a point. 

“I…am not sure if your human form of mating would suffice. At this particular time Keith may be unable to achieve release of his genetic material if you are not coupled in a way that appropriately stimulates the whole of Keith’s genitals.”

“Fuck.” Keith groans. 

“Hey, no, Keith. It’ll be fine. They’re not all that different from a textured dildo and people use those.”

“But you don’t,” Keith mutters into Shiro’s shoulder.

“I might have if I had one,” Shiro protests.

“We could just not and I could do the treatment thing, and get the creme to get these off. This sucks but we don’t have to-”

The doctor makes a harsh noise of objection and Keith falls silent.

“I believe that would be unwise.” 

“Why?”

“Because you have clearly already started to form a bond.” The doctor gestures encompassing both he new weird Galra biology problem triggered by the whole thing, and to the way Keith is curled into Shiro’s side, skin to skin as much as possible, and the cleaned and bandaged bite mark on Shiro’s neck.

“And what would happen if we don’t complete the bond?” Shiro asks levelly. 

The doctor vigorously shakes his head. “I can’t say for a human, but that has great negative impact for a Galra, both physically and psychologically. You have begun to combine your quintessence, to share a bridge between your cores. If this bridge is not completed it will become unstable, it can completely drain one of the partners, or worse.”

Keith feels like crying. Shiro’s arm is tight and comforting around him, but Keith can’t look at him. His stupid body, stupid Galra hybrid, Keith feels a sharp flash of hatred.

“Hey!” Shiro protests. He lifts Keith’s chin with a finger. “I love you. Maybe this isn’t ideal, but we’ll figure it out.” He sounds so certain Keith wants to believe him.

 

“I think that’s as stretched out as I can get myself,” Shiro says. He sits back on Keith’s thighs, looking down at Keith warmly. “I promise you, I’m going to go very slowly and if this hurts at all I will be stopping.”

“Yeah, don’t throw your self on that sword,” Keith snarks. Things feel a little more normal as Shiro grins back at him. Keith adds another palmful of the sliding-gel over his dick as well. Shiro lowers himself slowly over Keith. Keith gasps, biting his own lip hard. He clutches at the cushions and trembles to keep himself still. 

“Your amazing Keith,” Shiro says. “You’re always amazing.” Keith’s breath pants out of him in a soft, whining ‘ha’. Shiro sinks lower but he doesn’t stop.

“Are- are you okay?” Keith manages. Shiro’s eyes have fluttered closed and his head is tilted back. Shiro rolls his hips just a little and sinks a bit lower. Keith gasps again. Shiro echoes the sound and clenches around him.

“God, Keith.” Shiro groans and rolls his hips. “You do not need to use that creme.” 

Keith’s mouth drops open as he watches Shiro grind himself on Keith’s cock more enthusiastically. Keith reaches up to press an open, reverent palm to Shiro’s chest. Sensation crests over Keith like a wave. The room beyond Shiro blurs while Shiro remains in tight focus. Everything in the world is narrowing down to them, the places where they’re connected, the way Shiro is touching him, one hand coming to cup Keith’s cheek.

Keith turns his head into Shiro’s palm nuzzling against him. He sucks Shiro’s thumb into his mouth and bites down lightly, not enough to draw blood this time, just enough for Shiro to feel his teeth. Shiro curses and clenches hot around Keith. Keith’s second orgasm hits him like a bolt of lightening straight from the hot spurt of Shiro’s come on his chest to his own dick. Keith’s hips stutter, only able to move fractionally under Shiro’s weight. The drag of his cock inside Shiro is delicious with his release binding them together. Lines of light spiral through him everywhere Shiro is touching him. 

“It’s okay. I’ve got you. I love you.” Shiro is saying, leaning down to whisper kisses across Keith’s face. Keith realizes that he’s been begging again, a litany of pleas falling from his mouth half voiced. He blindly seeks out Shiro’s lips and silences them both.

They curl sideways to bask in the afterglow, Keith memorizing the familiar features of Shiro’s face and Shiro’s fingers softly stroking Keith’s hair back from his forehead. Keith hasn’t pulled out yet and little sparks are still zipping over his skin from where Shiro’s fingers brush his face and where Shiro’s thigh is resting over his hip. That’s fairly normal. It’s a little uncomfortable because it means Keith’s laying with Shiro’s leg tucked under the curve of his waist, but he’s too exhausted to manage more extensive repositioning. Besides, Shiro likes having Keith inside him after they’ve both come. It doesn’t last very long usually, but there’s something incredibly intimate about it that they both enjoy. After a while the sweat starts to cool on Keith’s skin and he’s sure Shiro’s leg beneath him is starting to go numb. Keith figures he’d better roll away and they can both get back to the Castle. Only, he can’t roll away. Keith stares at Shiro sure his face is reflecting his dawning horror. Shiro busts out laughing.

“He did say mating lock.”

“Oh my fucking god.” Keith mutters and tries to smother himself on Shiro’s chest. 

 

Thankfully it isn’t all that much longer before Keith’s dick goes soft enough that even with the apparently directional aspect of the new Galra feature to his dick, he can slowly ease his way out of Shiro without the spines locking them together. 

“I guess it’s a good thing you’re not very thrusty when I ride you like that,” Shiro observes.

“You like it,” Keith returns, feeling vaguely nettled. Shiro’s arm wraps around his shoulders, pulling him into a deep kiss. 

“I do.” 

Shiro is certainly walking a little funny as they make their, fully and completely clothed, way back to the medical room. 

“I am so ready to go home and take a nap,” Keith mutters. The doctor hurries over to them.

“Food first, I could eat a cow.”

“Kaltenecker would not appreciate that,” Keith grins, “but I’m not really hungry yet. More for you I guess.” 

“That’s not good,” the doctor says.

Keith suppresses a groan at the doctor’s concerned expression. 

There’s some sort of scan and a few tests. Shiro holds his hand this time too. At least Keith is much more focused this time around. Whereas before there was sort of only Shiro, this time it’s Shiro and everything else. Keith is still much more perceptive of scent than usual, and the lights of the medical space are rather brighter than he might regularly perceive them, but he’s well on the way to back to normal. The energy under his skin is mostly gone. He feels light and warm. He keeps looking at Shiro and smiling. Shiro is happy he realizes. He’s concerned sure, but he’s so overwhelmingly glad right now, so full up of love it’s spilling over, probably because Keith’s pouring it all right back at him. 

“I realize this may be a delicate subject,” the doctor says. 

“Because the rest of this whole disaster has been so appropriate.” Keith rolls his eyes. Shiro grins at him.

“Was he able to penetrate your childbearing organ?” 

“…I don’t have a child bearing organ,” Keith states flatly. 

The doctor pulls out the scanning device again and points out the location where Keith apparently does have some sort of vestigial version of the Galra organ. 

“True it’s positioning and size are somewhat different from typical Galra, I assume a result of your human influence. In fact, I’d imagine the possibility of you carrying offspring to birth is very low. This is often the case with hybrids.” 

Keith stares down at himself. “I could have gotten fucking pregnant.”

“It is possible, but I think highly unlikely. I do not think you could support a litter. And certainly there is no concern once we’ve administered the correct preventions.”

“Humans typically have only gestate one child at a time,” Shiro says, unhelpfully. 

“So we have to get Shiro to what?” Keith asks, returning to the immediately important point and hoping for some sort of divine intervention, even if all he’s feeling from Shiro is still that warm wash of love, now tinged with absolute hilarity and maybe a bit of hysteria.

“When you properly stimulated, the sphincter connecting the organ to you lower rectum should relax allowing it to be accessible. The, ah, mating bite tends to help trigger that relaxation. And the spines, which obviously I see you two can’t change. However, there are unfortunate Galra who are unable to form he spines who still reproduce or bond through reliance on the mating bite and manipulation of quintessence which both of you seem to be innately successful with thus far.” The doctor looks back down at his scanner. “Try the bite. I suppose I should have been clearer on that point.”

“Fine, alright!” Keith throws up one hand. He can’t throw both in the air because Shiro still has one. “Let’s do this.” 

 

Shiro starts snickering as they get undressed again. It’s a full chuckle by the time their both naked. 

“Sure, hilarious. This has been a great day for all of us,” Keith gripes. Shiro grabs him by the waist and tugs him in, pressing his forehead against Keith’s.

“I’ve spent it with you,” Shiro says. “I love you. I love having sex with you. It’s like a very weird vacation. I’m enjoying it.” 

Keith blushes and tilts his chin up just enough to brush his lips lightly over Shiro’s. “I see your point,” he murmurs.

Shiro lowers him tenderly down into the cushion pile. Keith goes along with the general making out for a while, even knowing they’re trying for _something_ , it’s nice not to feel rushed. They don’t have anywhere urgently requiring their attention. They aren’t fighting for their lives or rushing out for a rescue or working on the next piece of strategy against Zarkon’s Empire. It’s so very rare for there to be time just for them. But even if Keith would maybe like to, they can’t stay here forever. 

“Here,” Keith rolls so he’s on hands and knees, “I think this will probably be easier, just from what the scan seemed to show.” 

Shiro runs a gentle hand over Keith’s hip and the curve of his ass. “Are your knees comfortable? The cushions don’t seem that stable.”

“The floor under all this is weirdly springy too, at this point I’m not asking questions.” 

Shiro laughs softly against the back of his neck, blanketing Keith with his body. “Okay,” he murmurs into Keith’s ear. 

They still have the sliding-gel and Shiro works Keith open again. It’s easier since Keith is already relaxed and loose after what feels like two orgasms. His dick isn’t getting hard again, which he’s vaguely grateful for, but there’s still pleasure sparking through his body delightfully. Shiro pushes in hard from the start this time, a firm roll of his hips to the hilt. Keith groans deeply and drops his head down between his braced forearms. Shiro fucks him slow at first but with a steadily gaining pace. Keith’s body hums. The energy feeling from before is back. It weaves from his back to Shiro’s chest where Shiro bends over him and presses against Keith. It winds through the tight band of Shiro’s arm around Keith’s chest and where Keith’s shoulder brushes against Shiro’s Galra arm, braced to keep Shiro steadily supported over Keith. 

The feeling twines inside him, that same almost bursting pleasure. Keith feels needy, demanding as he rocks back into Shiro. Now that he knows there’s something there it’s almost like he can feel it. Keith is so very, very close.  
“The bite,” Keith gasps. “He said-” Shiro’s teeth clamp down at the join of the base of his neck back of his shoulder. Keith shakes. “Harder!” 

It’s so, so good when the bite breaks through. The pain lights up Keith’s spine and he howls. He is made up of nothing but energy. Every inch of skin Shiro has ever touched, which is every inch of Keith, is lit up like a beacon. Keith will live in the afterimage of this light and never be free. He will see every reverent touch Shiro has traced on his skin and he will live them, glowing with that pride, satisfaction, possession, and joy. 

Keith feels something inside him give. The sensation is strange, but at the same time everything Keith has been straining for. It’s just the tip of Shiro’s dick he thinks, maybe. Keith closes his eyes to just feel. Shiro is trembling over him. Fine tremors ripple from his skin to Keith’s. 

“Keith,” Shiro says, strangled.

“Am I hurting you?” Keith manages to get out, breathless.

“Fuck no.” 

Keith’s next shuddery inhale and exhale are audibly relieved. Or maybe it’s just that Keith can feel Shiro through the forming bond. Shiro is awed and also completely and utterly turned on. 

“Well, your boyfriend is officially an alien,” Keith says. He cranes his head back over his shoulder because Shiro’s desire to kiss him is so strong, or maybe it’s Keith’s desire reflected in Shiro. The more he feels the more confusing the boundaries of his own body are becoming. He feels his cock jerk, but he’s still soft and Shiro is the one twitching inside him. He feels Shiro’s lips against his own, and the softness of his own hair under Shiro’s fingertips. Shiro’s pleasure amplifies through him and straight back to Shiro. Keith is just wondering if they could come from this, Shiro nearly still inside him and pleasure reverberating between them, when Shiro does. Shiro comes inside him, held safely within Keith’s body and Keith feels it in his core. 

Keith is completely limp afterwards, wrung out and just _done_. He is also discovering what Shiro meant about wanting to eat a cow.

“I’m dead,” Keith declares.

“I can feel that you’re not,” Shiro says. The air between them hums with Shiro’s fondness. “Why don’t we go check with the doctor to verify that we actually managed it this time.”

“Ugh, fine.” Keith awkwardly clambers to his feet, but he stops to kiss Shiro slowly and thoroughly before getting fully dressed.

 

“Yes, excellent. You do seem to grasping the emotional impact of the bond quite well. Galra generally take more time to use it to it’s full potential. Humans certainly are different.” The doctor hums, looking over a few readouts from his final round of tests. “Yes, you’ll want to go home and eat, drink, and rest. You’ll feel desire to remain in close physical contact for a while. That is typical but unnecessary unless you desire to. You will of course want to make sure you couple frequently to prevent repeat fertility problems.”

“How frequently.”

“Oh every few movements. More than once a phoeb at any rate.”

“More than once a month,” Keith repeats flatly. He cannot believe how stupid this whole thing is. If they had only- Shiro’s hand on his forearm squeezes placatingly.

“I’m sure we can manage that,” Shiro agrees. 

“I’ll give you more of the conception blocker. You’ll want to administer it twice a movement for the next few pheobs.” 

“What! Why?” Keith demands.

“You live in a resource rich environment, but you are both under undue stress” the doctor explains.

“We’re not sure what you mean,” Shiro frowns. 

“Your fertility has abated and will now shift to dormancy, however there is still a slim chance of conception in the next few pheobs. Galra can store genetic material for breeding for a reasonable period if in a state of stress. When the body is no longer under threat from scarcity or hostile environment, conception may occur. It’s a very slim chance, particularly given your particular anatomy, but it’s better you take the medication for the next while just to be sure. One drop in food is all that’s necessary. It’s just enough to keep your current blocker active till we can be sure any remaining genetic material has been fully absorbed and repurposed by your body.

“I am not explaining this to everyone at dinner,” Keith says. He takes the vials the doctor holds out. 

 

The ride back to the Castle is quiet. The star field is the same dark expanse of space as it was before. Keith climbs into Shiro’s lap after the tricky bit of the piloting is over with and tucks his head against Shiro’s throat. Shiro still smells good, but it isn’t as heady or all encompassing. Shiro’s arm is comforting around his waist but it isn’t a hot brand arcing energy against him. Keith is quiet and happy. 

Keith suddenly realizes something. He sits up sharply.

“I love you!” 

Shiro looks at him nonplused. 

“This wasn’t how I meant to tell you either, but I completely failed to tell you! I do. I love you.” 

Shiro smiles. “I know.” His arm around Keith’s waist squeezes gently. “I knew before I could feel it, too.”

“I should have said,” Keith shakes his head.

“You were a bit distracted.” 

Keith laughs, “I guess you’re right. …You love me.” He says it softly, certain but still a little wondering into the quiet space between them in the lion.

“I do,” Shiro says. Keith can feel the answer before he says it.

**Author's Note:**

> Research for this was mostly academic papers on galago reproduction, also some on felines and bats, all for some informed hand waving *ta da*… So the xenobiology for Galra in this fic is a mishmash of aspects of a couple of different species + obviously some ‘what if that means…' ideas. I’ll admit I didn’t put a whole lot of time into the Galra homeworld and ecological niche of origin to how they got where they are today, but hey it’s porn and they’re aliens. *finger guns and backs away from stack of scientific papers*


End file.
